This invention relates to the detection of activated human T-lymphocytes ("T-cells").
Mature human T-cells can exist in a non-activated "resting" state, or in an activated state. Human T-cells can be activated by either of two lineage-specific surface components: the antigen/MHC histocompatibility receptor complex (T3-Ti), and the unrelated T11 molecule. The antigen/MHC receptor complex is comprised of two clonally unique polypeptide chains, termed alpha and beta, which form the putative binding site for antigen/MHC and three noncovalently associated 20-25KD monomorphic T3 molecules thought to be involved in signal transduction. The second structure, the 50KD sheep erythrocyte binding protein, appears to be phylogenetically and ontogenetically more conserved. Although the natural ligand of the T11 system has not yet been identified, monoclonal antibodies to two sets of epitopes, T11.sub.2 and T11.sub.3 (and to a lesser extent, T11.sub.1 and T11.sub.3), in concert induce T-cell activation.
T-cells are activated in vivo in response to a variety of stimuli, including infectious agents and sources of foreign antigens, e.g., allografts. The capacity of a patient's T-cells to be activated via the T3-Ti and T11 pathways is an important indication of the status of the patient's immune system. In addition, activation of a patient's T-cells in response to contact with cells from a potential donor of a organ such as a kidney or heart, or of cells, e.g., bone marrow cells, is an indication of histoincompatibility which would lead to rejection of the allograft. Similarly, activation of the donor's T-cells cells indicates probable graft-versus-host disease. Because of the risk of these often fatal developments, histocompatibility typing (known as MHC typing) must be carried out prior to organ or tissue transplantation procedures, often delaying the procedure for several days.